William emanuel sundberg



(No ModeL) W. E. SUNDBERG. TELEPHONE TRANSMITTER.

Patented June 14,1898.

Inventcr. w. 6. W

Witnesses.

w M kgr a Attor neys,

UNITED I STATES PATENT OFFICE.

WILLIAM EMANUEL SUN DBERG, OF W'ORCESTER, MASSACHUSETTS, ASSIGNOR TO LARS M. PETTERSON AND CARL J..EKSTEDT, OF SAME PLACE, AS TRUSTEES FOR THE RELIABLE ELECTRIC MANUFACTURING COMPANY.

TELEPHONE-TRANSMILI'TERI.

SPECIFICATION forming part of Letters Patent No. 605,832, dated June 14:, 1898.

Application filed September 28,189'7- Serial No. 653,402. (No model.)

To aZZ whom it may concern."

Be it known that I, WILLIAM EMANUEL SUNDBERG, a subject of the King of Sweden and Norway, residing'at. Worcester, in the 5 county of lVorcester an'd'State of'Massachusetts, have invented a new and useful Improvement in Telephone-Transmitters, of which the following is a specification.

My invention relates to that class of tele 1o phone-transmitters which em ploy granulated granulated carbon with a contact-plate having a serrated or roughened face, which will I 5 provide a comparatively large area of contact for the powdered carbon, to provideimproved means for confining the powdered or granulated carbon between two contact-plates, and to provide a detachableconnection for secur- 2o ing the transmitter-casing to a socket-piece, so that the transmitter can be readily removed from the socket-piece.

To these ends my invention consists of the parts and combinations of parts, as hereinaf- 2 5 ter described, and more particularly pointed out in the claim at the end of this specification.

In the accompanying drawings, Figure 1 is a transverse sectional view of a telephonetransmitter constructed according to my invention, and Fig. 2 is a detail view of one of the carbon contact-plates.v

A telephone-transmitter constructed according to my invention preferably comprises 3 5 two carbon contact-plates, one of the carbon,

'45 ried by one of the carbon plates and is arranged to engage tapering or chamfered edges of the other contact-plate in such a manner as to prevent the powdered carbon from working out of place and becoming lodged between the diaphragm and the contact-plate carried thereby; r A

My telephone-transmitter casing is preferably rot-atably mounted in a suitable socket,

readily removed from its socket-piece when ,is connected to a spring contact-arm and the terminal 14 is connected to a metallic 'piece16, which engages the socket 10.

The transmitter-casing which I employ is preferably substantially cylindrical in shape and is provided with an extension or stud adapted to fit into the socket-piece 10, the transmitter-casing being rotatably held in place by means of a screw 19, engaging an annular groove 18.

Extending from the front of the transmitter-casing 17 is the ordinary mouthpiece 20, and arranged opposite the mouthpiece 20 is a diaphragm 21, which is adj ustably held in place by means of light springs 30, so that the same may be vibrated by the sound-waves acting thereon through the mouthpiece 20.

In order to prevent the diaphragm 21 from corroding, I preferably provide an annular moisture-excluding felt washer 22, which is arranged so that a comparatively small surface of the diaphragm 21 will be exposed to the atmosphere.

A carbon contact-plate 31 is secured to the center of the diaphragm 21 by means of a rivet 32 Mounted on a diaphragm 33, at the rear of the transmitter-casing 17 and insulated therefrom, is a second carbon contact-plate 35.

The contact-plates 31 and 35 are preferably molded or formed from carbon and are pro vided with roughened faces preferably formed by concentric annular projections, and the diaphragm 31 may also be provided with small pockets or depressions, as shown most clearly in Fig. 2.

An annular felt washerlll is mounted upon the carbon contact-plate 85, so as to confine a body of powdered or granulated carbon between the contact-plates 31 and 35. At its outer end the annular felt washer 3i engages a ehamfered or inclined edge on the plate 31, and I have adopted this construction especially with aview of preventing the powdered carbon from working out from between the contact-plates 31 and 35 and from becoming lodged between the metallic diaphragm 21 and the contact-plate 3]. carried thereby.

Extending from the contact-plate 35 is a metallic rod 36, which extends through an insulating-bushing 37. Threaded onto the rod 36 are ad justing-n uts,whieh can be turned so as to adjust the distance between the carbon contact-plates 31 and 35. Atits end the metallic rod 36 engages the spring-terminal 15, before referred to. By means of this construction it will be seen that the transmittercasing can be readily removed from its socket without detaching or changing the electrical connections.

By providing the carbon contact-plates 31 and 35 with serrated or roughened faces I have provided an increased area of contact between the powdered carbon and the contact-plate, so that the vibration of one of the contaet-plates will cause considerable variations in the resistance to the electric circuit, and also on account of this construction there will be less liability of the powdered carbon caking or hardening.

I am aware that changes may be made in the construction of telephonetransmitters by those who are skilled in the art without departing from the scope of my invention as expressed in the claim. I do not wish, therefore, to be limited to the construction which I have shown and described; but

What I do claim, and desire to secure by Letters Patent of the United States, is

In a telephone-transmitter, the combination of a casing 17 having a mouthpiece 20, a metallic diaphragm 21, a plurality of screws having springs adjustably coiled thereon for holding the diaphragm in place, a contactplate 31 carried by said diaphragm, a diaphragm S3,a contact-plate 35 secured thereon, a central adj usting-serew having nuts for regulating the distance between said contactplates, a body of powdered carbon confined between the eontactplates, and a felt washer 3t secured 011 the contact-plate in position to confine the body of powdered carbon, and to engage an inclined or chamfered edge on the contact-plate 3 substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

WILLIAM EMANUEL SUNDBEIH \Vitncsses:

PHILIP W. Sou'rnon'rn, .T. BRAINERD IIALL. 

